The present invention relates to a semiconductor device utilized in the television industry and so forth and particularly has reference to a solid-state color image sensor having a photodiode.
At present as such a solid-State image pickup device, there is an available solid-state color image sensor of on-chip color filter type/filter-bonded type.
Heretofore, in the semiconductor device formed on a silicon substrate, for proofing against moisture which causes corrosion of metal, generally the surface of the device is protected with an SiO.sub.2 film and further hermetically sealed by packaging.
If there exist any stains on the SiO.sub.2 film, various troubles take place. For example, in the case of a solid-state color image sensor, if any stains exist on the surface of the image area region, the stains manifest themselves as shadows on the image, and raise a problem of defective image. The semiconductor device covered with an insulating film such as the SiO.sub.2 film left in as-formed state, tend to be charged with electricity, so that the stains, such as dust and the like, tend to stick on the surface of the device. It is particularly liable to be charged in the assembling step of putting the semiconductor device into a package.
In this connection, applying an antistatic agent or forming a transparent resin layer containing an antistatic agent on the top surface of the semiconductor device has been proposed. According to this proposal (Japanese Patent Application No. Sho 59-92338 (KOKAI No. Sho 60-58681) the top-most surface of the semiconductor device or the on-chip color filter type semiconductor device is subjected to this treatment.
Besides, the color filter is made of an organic material. There is a possibility of microbes generating and propagating in the organic material. Soiled front and back surfaces of the sealing glass plate also cause the generation and propagation of microbes. For averting such occurrences, uniform coating of the top surface of the color filter or the sealing glass surfaces using a transparent resin containing an antimold agent, is proposed (Japanese Patent Application No. Sho 58-167731 (KOKAI No. Sho 60-58681).
However, such a film is a protective film formed by casting or spin coating. In this way, it is difficult to form the film having a thickness of the order of nanometer. Moreover, there is a problem that the protective film, formed as a thin film, tends to be removed off the surface.